Transmission fix finally for 14-15 sierra silverado! WOOOOT!

[J-man67]

Mass production at its finest...

[ember1205]

I have never had a perfect GM product (and gosh I have had lots of them). My 15 Denali, while slow to shift in town seems fine, but could be better. However my 2010 Denali had a gremlin where it would magically go out of gear at random times, no codes, finally got lucky and it froze in 1st (though the whole time they said it was because I was driving conservatively (like a grandma...gas was 4.50 a gallon what do ya expect). GM came and took the transmission and gave me a new one at 10k miles. Still at times with foot to the floor it seemed to want permission to upshift to use those 403 ponies it had. The 15 does not behave that way at all. The only gm truck products where I had no issues with shifting is with the Yellow Z06 Corvette in the garage.....that's a manual (wish I could get one in the 15 Denali) (but I have had other gremlins to deal with in the vette too).

 

Its not just gm...

 

My acura had to have its transmission replaced

The Honda too (same problem when they went to v6s with the 6 speed)

My f150 had horrible driveshaft vibration

My Audi had peeling trim at the doors at 20K

1 had a POS ford probe that went through 2 turbos

My water pump failed on my toyota Tacoma

on and on....

 

The only cars that really worked were made before 1972.

 

The problems with your Hondas (that includes the Acura) is because of their tranny design. Reverse shares some components with forward. If you don't have the car at a dead stop before switching between the two, you cause premature wear on the transmission and it will fail early.

[07Softail]

My truck shifts not bad except fot the 150 rpm bounce. Seems to happen around 30-45 mph, but doesn't do it all the time.

I just notice that my truck did this today when leaving work. Steady throttle on the 3-4 shift 35-40mph and 2500rpm and it flashed up 500rpm so at that point it was at 3000rpm...Almost felt like a loose torque converter and i tried to replicate it and never could.

 

RT

[Skeeter McSkeet]

I think the truck drives a lot better if you put your foot into it. I've noticed if I have the cruise set and come to a stop, when I resume it, the truck really gets on it pretty good. It accelerates quicker than I normally would from a stop, now I just get on it as well lol.

 

I've been using M5 in town driving 35 or less, and it has been doing pretty good for me.

 

Edit* you guys that have the tune with tow/haul, are you still able to use tow/haul if you need to and disable the tune?

 

-Skeet

[BlackZ71Silverado]

My guy isn't on the forum, and honestly I don't want to get him in any trouble as I feel he did this more as a favor than anything if you know what I mean. So sadly I would like to keep my source anonymous. He again relayed as soon as this is close to fruition that he would advise. Don't mean to dangle the carrot in front of anyone.

Seems like 'your guy' may have pulled a fast one by tuning your truck and claiming it's a GM beta test program that only he knows about.

Seeing how you say he has experience with several different tuning programs, I would be willing to bet he used EFI Live or similar to tune your transmission while he had your truck.

I know you said you would not buy a tune due to warranty concern but with 'your guy' working at the dealership, he would be the person to approve warranty work. I highly doubt he would deny work due to his own tune that he has you thinking is a GM test file that only he had access to.

There are members here from all over the country who have asked their dealers about this claimed update and nobody has a clue. Why would only one person who works at a GM dealership know what not one other employee nation wide has any clue about?

Sounds like a fairy tail to me and it's not your fault, you may have been fooled. For the sake of the 14-15 owners, I hope an update does actually come out to help you guys out. If not, you can always have it tuned to your liking.

 

OP, can you go to a different dealership and have them read your truck programming and see if it is in fact tuned by 'your guy'. Any service dept. can tell you the GM program version your truck is running. They can also tell you if the truck is running non-GM software. I don't own a 14-15 truck but I am curious as to what the truth is with this story.

 

 

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[rhodeislandhntr]

mine is still acing a little weird, 6100 miles now and was just wondering if any one has changed to a different tranny fluid and seen either the same or better performance. I was thinking about going to Valvoline Dexron IV full fluid change to see if there is any change but wont have it done for another month or so.

[BOOMER119]

Exactly! I made an appt for Monday AM to drive with a tech and drive a truck with a gear ratio other then 3.73s. We'll see. Said he didn't have any other complaints but I drive a lot more then the average person and I'm very "in-tune" with my trucks.

 

Let us know how you make out.

 

As for the gear ratio, I believe this is clearly a tranny issue versus a rear axle issue. I say that as this problem seems pretty universal despite axle ratio. I have 3.08's, I believe you have 3.73's and there are many through this thread with 3.42's.

 

Having the 3.08's I was really kicking myself for doing this due to the driveability issues. I wanted 3.42's but the dealer talked me into the 3.08's. That being said, seeing that this issue is universal despite axle gearing, to me it's more of a tranny issue than the axle ratio. Now I don't feel quite so bad about the 3.08's.

 

At any rate, good luck on Monday and let us know.

[Badnewcastle]

Following, well hell, I might as well since everyone else is with the 5.3/3.42/six speeds.

[FL335i]

Shifting in my '14 is fine. Yes, GM is programming them for MPG's, but still decent. The V4 mode is what's killing us here guys. I shimmed my gas pedal so the bracket doesn't flex and I have a AFE cat-back exhaust the truck is a different animal. When it's in V8 mode the thing is crisp and responsive. goes into V4 feels like a turd. I don't mind V4 on the Hwy. I wish V4 only kicked in at speeds OVER 50mph. That would fix a lot of the "feel" when driving around town. All I want is V4 mode under 50mph disabled. Tranny is fine. My truck is averaging a solid combined 20mpg. The catback added at least 1mpg. I normally averaged 17.5-18 to the tank. Now I'm doing 19.5-20.5 to the tank, same weekly commute.

[rmart]

I wish AFM was a toggle on|off option...

I like the 16.5mpg (400 mile avg) I'm getting out of my 6.2 with .373 but every now and again I'd like it to jump when I put the spurs to it.

[hotrodz37]

I wish AFM was a toggle on|off option...

I like the 16.5mpg (400 mile avg) I'm getting out of my 6.2 with .373 but every now and again I'd like it to jump when I put the spurs to it.

It can be essentially. Whenever I don't want it to go to v4 I put it in M5 and it cuts out afm. Not much good past 55mph or so but anything under that it's perfect. I often drive around town in m5 and no issues here!

 

 

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[dbannerz71]

I think it just takes a little getting used to. Now granted, some of you guys who are saying that your transmission is clunking and slamming into gears and doing all these different flares, I've had none of that and I have the 3.08 gears also. what I do notice is that when you go to give it gas if you're driving around town is that sometimes when its in V4, it feels as though it's doing a double down shift. One time to get it to v8, and then again to actually shift down one gear. This causes what feels like a delayed response. One other thing to note is that I have been running E85 lately and I have noticed a substantial performance increase. Both in hard throttle situations and partial.

[5RWill]

I have no problem as to how smoothly it shifts. I have a problem with how it is geared towards conservative mpg, ultimately handicapping the 5.3. If I made a vehicle purchase based on mpg I would've gotten a Prius or went Ecodiesel. I bought the truck with the intention of using it like a truck. Of course for 600$ a tune will fix this. Then you get into warranty game.

[Silverado-Hareek]

I was heading down a highway at around 55-60 mph, stop light turned red ahead of me so I let off to coast, because usually that light will turn green again by the time you get to it from where I was. Sure enough, light turned green when I was about to hit the brakes. Hit the gas going around 20-25 mph and felt like it was in neutral or something. Took a second or so for it to respond to me pressing the pedal, then I could almost feel it pulling like a roller coaster would going up the first big hill like a chug-a-lug type of feel. This was on basically flat ground.

 

 

-Skeet

Yep I can't stand this either. I feel like the AFM makes it even worse. It's like the hesitation/neutral feeling happens because you're in V4 and the switch back to V8 needs to occur first before the transmission senses the amount of throttle you're really giving it to downshift and go and this series of events is a lot for the system to process. In other words both the V8 kicking in and the downshifting of the transmission won't occur at the same time when you press the throttle, they have to happen in order....one before the other....and the system is very slow at processing that order.

 

A friend of my brother in law is a salesman at a Chevy dealer and I was complaining to him once about how i don't like the design of M mode in that it caps the number of gears the auto tranny will shift through instead of being a true on-demand gear shifting system like other manufacturers have and he said they design it that way to protect the transmission. I'm wondering if this hesitation/neutral feeling we're talking about here is due to GM efforts to protect the transmission and doesn't have anything to do with fuel economy at all.

 

 

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[fondupot]

I'm wondering if this hesitation/neutral feeling we're talking about here is due to GM efforts to protect the transmission and doesn't have anything to do with fuel economy at all.

 

Probably. A lot if the way it functions is to prevent driveline lash, which supposedly lengthens the life of the drive train.